Does an Expert Witness Enjoy Immunity from Suit?

This was the primary issue in Karling v Purdue (Opinion of JG Reid QC dated 29th September,
sitting as a Temporary Judge; available on the Scottish Court of Session website -
(www.scotcourts.gov.uk).
K was convicted of murder in 1995 but the conviction was eventually quashed on appeal. P had
been engaged by K to provide an expert opinion for use in K's defence. In the present case, K
was suing P for damages for breach of contract and negligence. Was P immune from such suit being
an expert engaged in such circumstances?
In a lengthy Opinion, Mr Reid QC surveyed ...